<template>
    <p>count值为：{{ count }}</p>
    <button @click="add">加n</button>
  </template>
  <script setup>
  import { ref } from 'vue'
  const emit = defineEmits(['updateCount'])
  const count = ref(1)
  const add = () => {  count.value++ 
    emit('updateCount', 2) }
  </script>
  